Adolph Rickenbacker invented the electric guitar. The popularity of the electric guitar began with the big band era as amplified instruments became necessary to compete with the loud volumes of the large brass sections common to jazz orchestras of the thirties and forties. Initially, electric guitars consisted primarily of hollow archtop acoustic guitar bodies to which electromagnetic transducers known as pickups had been attached.
Electric guitars, in contrast to acoustic guitars, rely upon movement of strings in operative proximity to a pickup to convert the oscillations of a string into electrical impulses for subsequent conversion into sound. Some hybrid electric-acoustic guitars are also equipped with additional microphones or piezoelectric pickups (transducers) that sense mechanical vibration from the body. The guitar's magnetic pickups are embedded or “potted” in epoxy or wax to prevent the pickup from having a microphonic effect.
In 1950, electronics and instrument amplifier maker Clarence Leonidas Fender, better known as Leo Fender, designed the first commercially successful solid-body electric guitar with a single magnetic pickup, which was initially named the “Esquire™”. A deluxe version of the Esquire™ included two single-coil, 6-pole pickups (bridge and neck positions) with tone and volume controls, a pickup selector switch; an output jack mounted on the side of the body. A black bakelite pickguard concealed a number of body routings for pickups and the connecting wiring. This deluxe version of the Esquire™ was initially called the “Broadcaster™” but because Gretsch® had a drumset marketed with a similar name (Broadkaster™), Fender® changed the name to “Telecaster®” In 1954, Fender® introduced the Fender® Stratocaster®, or “Strat” as a further deluxe model having an integrated vibrato mechanism, three single-coil pickups, and body comfort contours. A five-way switch allowed the selective activation of combinations of the three pickups to selectably alter the resulting sound.
By 1957, Gibson®, a rival manufacturer had made a major change to its deluxe electric guitar, the “Les Paur” Gibson® included a novel pickup known as the “Humbucker®” The Humbucker®, invented by Seth Lover, is a dual-coil pickup whose two windings are connected out of phase and reverse-wound. The dual coils tend to cancel a 60-cycle induced signal emanating from appliances using 60-cycle power. A Humbucker® also produces a distinctive, more “mellow” tone which appeals to many guitarists. The same effect can be achieved on guitars, such as the Fender® Stratocaster®, when two single-coil pickups are selected to be active at the same time to cancel the hum. As is evident in this discussion, progress of the electric guitar has been marked by the progress in selection and configuration of the several pickups used to generate the characteristic signal.
Pickups exploit induced currents in windings to create the signal. Within a pickup, a magnet is located under each steel string. When a string oscillates at a certain frequency in the presence of the magnet, a magnetic field between the string and magnet oscillates. An electromagnetic coil of wire is wrapped around each magnet such that the oscillating magnetic field induces an alternating current at the same frequency within the coil. Selections of materials, such as numbers of windings in the coil, composition of permanent magnets, and dimensions of the several components, give distinct tonal qualities to various models of pickup.
More recently, many semi-acoustic and acoustic guitars, and some electric guitars and basses, have been fitted with piezoelectric pickups instead of, or in addition to, magnetic pickups. The piezoelectric pickup gives a very wide frequency range output compared to the magnetic pickups and can give large amplitude signals from the strings. The piezoelectric pickup has a very different sound, which some guitarists prefer, and do not receive the 60-cycle hum that affects magnetic pickups.
A guitarist will often select from among various pickups, a set of pickups which match the tone the guitarist desires to produce when performing a musical selection. Removal and replacement of pickups is a generally technical process including removing the strings, detaching each pickup from the guitar body, and disconnecting and connecting the pickups from internal electronics within the guitar body. Given the elaborate process necessary for replacement of the pickups, a guitarist's ability to meaningfully compare the relative tonal qualities of distinct sets of pickups is not possible.
Several inventors have taught mechanisms configured to allow ready removal and replacement of pickups in dockable modules. U.S. Pat. No. 4,425,831 to Lipman, U.S. Pat. No. 5,029,511 to Rosendahl, U.S. Pat. No. 5,252,777 to Allen, U.S. Pat. No. 4,872,386 to Betticare, U.S. Pat. No. 6,253,654 to Mercurio, U.S. Pat. No. 5,563,823 to Dodge, and U.S. Pat. No. 4,854,210 to Palazzolo each teaches modules that are removed by movement perpendicular to a plane the strings define. For instance, Mercurio teaches a rectangular shaped, through-the-body cutout between the neck and bridge to allow the insertion of a module from behind the instrument, drawing the module toward the plane of the strings. Mercurio teaches removal achieved by withdrawing the module away from the string plane through a through-the-body cutout.
Where movement perpendicular to the plane the strings define is required, only two routes are available, into or out of the guitar body. Movement out of the guitar body as taught by Betticare, Rosendahl, Allen, Lipman, and Palazzolo requires the removal and replacement of the strings along with the necessary retuning of the strings before the guitar can be played. Movement into and through the guitar body as Dodge and Mercurio teach, require the guitarist to remove the guitar from the playing posture as a prerequisite to changing the pickup. In either regard, the guitarist is hampered in comparison because of the transient nature of human recollection of sound. The longer the interval between use of one set of pickups and use of a second set of pickups, the less complete the guitarist's recollection, thereby impairing the ability to select the appropriate pickups.
What is missing in the art is an integral module that is readily removable and replaceable to facilitate the comparison of different pickups.